This invention relates to a bi-directional seal means having application in valves, particularly in butterfly valves. Butterfly valves have several advantages over other type valves in the regulation of fluid flow including low cost of manufacture, quickness of opening and minimal restriction to fluid flow when fully open. However, these valves generally have been limited to low pressure applications because of the inability to seal tightly at high pressures. In some prior art valves, the seals are located in grooves in the valve body and often these seals become dislodged when the valve is open permitting fluid to flow around the seal and dislodge it. In still others, high pressure fluid may leak through the valve by flowing between the valve body and seal. In many prior art valves contact between the disc and valve must be made so tight to prevent leakage that opening the valve, particularly large diameter valves, requires a large torque. Moreover, many prior art valve are not truly bi-directional, in that, they do not exhibit uniform performance characteristics to fluid flow in both directions. In addition, the seals in many commercially available valves comprise a plurality of complex parts, thereby increasing the cost to manufacture, the likelihood of manufacturing defects and the possibility of misalignment during assembly.
It is an object of the present invention to provide an improved bi-directional valve seal assembly which will not leak under high pressure and which is operable with a relatively low torque.
It is a further object to provide a reliable, relatively inexpensive valve seal assembly.